The invention relates to a vehicle seat with a seat carrier, with a buckle of a safety belt positioned thereon and with a vertically adjustable underframe, said underframe being provided with a sector gear and said seat carrier having an engaging element arranged thereon which is designed to cooperate with the sector gear and which under normal circumstances is in a position of rest in which it is spaced from the sector gear and the buckle being connected to an upper end of a means with tensile strength that is connected to cooperate with the engaging element so that, in an accident situation, the engaging element engages the sector gear.
This type of a vehicle seat forms the subject of DE 197 40 043 A.
The advantage of this kind of a vehicle seat lies in the fact that the buckle is positioned directly on the seat carrier. When the vehicle seat is adjusted in height, it maintains its position for a user. Accordingly, the user can find the buckle at always the same position, irrespective of the adjustment.
The problem with a buckle positioned on the seat carrier of a vertically adjustable vehicle seat is that, when the vehicle in which the vehicle seat is installed is involved in an accident, very high tensile loads must be transmitted from the buckle to an underframe of the vehicle. According to the prior art, sector gear and engaging element mesh, said mesh only taking place in an accident situation. Once engagement is accomplished, the buckle is connected to the underframe in such a manner that it resists tension, the connection passing through the means with tensile strength, the sector gear and the engaging element as well as a couple of rails of the longitudinal adjusting device into the underframe of the vehicle. Under normal driving circumstances, no engagement occurs so that the vertical adjustment can be actuated without collision or any other impairment, diverting the forces in the manner described.
An accident situation of a vehicle in which the vehicle seat is installed in this context means a situation in which acceleration is so high that a control switch of an air bag becomes responsive.
With the previously known vehicle seat, a sufficiently strong tensile load, as it just only occurs in accident situations, must actively act on the buckle to bring about the engagement described. The means with tensile strength needs to move a short distance to engage. This distance of movement is lost for decelerating and restraining an occupant. Additionally, under normal circumstances, the safety belt is not placed as tightly on the user as it would be desirable for his restraint and deceleration in the event of an accident.
It has become known to utilize what are termed belt tighteners with a driving cylinder that are triggered by the control switch in the event of an accident and already respond before the user, on account of his inertia, actually loads the safety belt. However, this previously known solution has the disadvantage that the position of the buckle is not related to the seat carrier, but to the underframe. The position of the buckle changes with vertical adjustment.
This is were the invention is setting in. It is its object to improve the vehicle seat of the type mentioned herein above in such a manner that, in the event of an accident, engagement is already actuated when the user has not yet moved with respect to the vehicle seat, the positioning of the buckle relative to the seat carrier being maintained, and that the safety belt can additionally be tightened in order to reduce the play in the safety belt.
In view of the vehicle seat of the type mentioned herein above, the solution to this object is to provide the belt with a tightening unit that has a driving cylinder, to deflect the means with tensile strength in its direction at a point of deflection in such a manner that a lower portion of the means with tensile strength runs substantially in longitudinal direction of the side part, to have the other end of the means with tensile strength arranged on the driving cylinder and to provide a holding means for the tightening unit on the side part.
So, according to the invention, a tightening unit with a driving cylinder is used, which may also be described as a buckle tightener or a belt buckle tightener. As it has been known in principle from other previous publications, it is utilized to rapidly pull the buckle downward in the initial stage of an accident situation, so that the safety belt is caused to tighten and is better capable of absorbing the later occurring relative motion of a user relative to the vehicle seat.
According to the invention, the tensile strength of the driving cylinder is now used to force the sector gear and the engaging element into mesh.
Accordingly, the particular advantage of the invention is that triggering the buckle tightener not only causes the belt to tighten but also brings about the positive engagement between sector gear and engaging element. If any, this engagement requires only a short portion of the range of movement of the belt buckle or a small pivoting movement of the belt buckle tightener, the belt has still enough distance to move for tightening, or the buckle tightener is designed with an accordingly longer distance of movement, respectively.
On account of the deflection, the means with tensile strength, which is more specifically designed as a steel cable, has an upper portion running between buckle and point of deflection and a lower portion running between point of deflection and driving cylinder. The two portions are relatively angled, they are typically arrayed in the shape of a V. On triggering the driving cylinder, the means with tensile strength moves relative to the point of deflection. The buckle is drawn downward. These movements or the forces or reaction forces generating these movements are now utilized to bring about the engagement between the engaging element and the sector gear. Several possibilities lie within the scope of the invention, some of which are explained herein after without any claim for exhaustiveness.
First, the buckle tightener can be fixed together with its driving cylinder in a swivel joint on the side piece in such a manner that a certain tilting motion about the swivel joint is possible. It is fastened by a bolt. The deflection of the means with tensile strength occurs at this bolt. The fixation is executed in such a way that, at normal operation, the buckle tightener cannot pivot about the bolt. On triggering the driving cylinder, the forces produced are so high that the buckle tightener pivots about the bolt. This pivoting movement is utilized to cause the engaging element and the sector gear to move into mesh. For this purpose, the engaging element for example is attached to the buckle tightener itself so that it pivots together with the latter. This pivoting movement is utilized for engagement.
Second, the driving cylinder can be connected to the remaining portions of the buckle tightener, more specifically to a deflection housing, by way of a deformable holding device. Prior to its actuation, the driving cylinder is at first spaced from a deflection housing by a greater distance and is supported by said housing by way of a holding device. The holding device transmits the reaction force. On triggering the driving cylinder and only in the event a resistance is opposed to the tensile strength in the means with tensile strength and thereby in the belt that is sufficient and is only experienced when the belt is tightened against a passenger, the holding device is deformed in such a manner that the driving cylinder comes nearer to the housing of the buckle tightener. This movement is utilized to cause the engaging element and the sector gear to move into mesh.
Third, it is possible to allow deflection to take place on the engaging element itself. When the driving cylinder is fired, the then effected traction in the means with tensile strength produces a high force at the point of deflection which is now realized by the engaging element. The engaging element is thus moved, e.g. pivoted, the sector gear is engaged.
Fourth, it is possible to provide for the engaging element in proximity to the deflection point at a place at which it at least slightly deflects the lower portion or the upper portion. When a tensile force occurs in the means with tensile strength on account of an actuation of the driving cylinder, a force is exerted onto the engaging element.
Fifth, it is possible to utilize a rotation occasioned by the actuation of the driving cylinder at the point of deflection to move an engaging element into mesh with the sector gear. The means with tensile strength encompasses a rotatable bolt at the point of deflection for example. The rotatable bolt is rotatably connected to the engaging element. In another design, the rotatable bolt has a projection that abuts a stop of the engaging element. As soon as the rotatable bolt is rotated, the engaging element pivots into the position of engagement.
All the alternatives that have been discussed may also be realized in mechanical reversal by moving the sector gear against a more or less stationary engaging element.
In a preferred development, the sector gear is executed on a curved sword that is hinged to a seat rail of the underframe. On account of the hinge, it may adopt such a position when the seat carrier is adjusted in height that under normal circumstances it does not move into mesh with the engaging element.
In another, preferred embodiment, the underframe has a rear swivelling prop to which the seat carrier is hinged in such a manner that it is pivotal about an axis. The sector gear exhibits a course that is concentric about the axis and is non-rotatably connected to the swivelling prop. The advantage of this embodiment is that the sector gear always keeps the same spacing from the engaging element that is arranged on the seat carrier. As a result thereof, it must not try to find and adopt somehow the right position.
In a preferred embodiment, the engaging element is additionally connected to the seat carrier by way of a positioning means that is for example designed as an elastic means or as a destructible means. This positioning means is overcome in the event of an accident. It serves to maintain the engaging element in its position of rest. In an accident situation, the positioning means is overcome so that the engaging element can act, it may for example pivot about a hinge joint, until it positively engages the sector gear. The positioning means may for example be a shearing pin that is destroyed on triggering the buckle tightener and on releasing the resulting force which then acts on the engaging element. The positioning means may also be a spring that pulls the engaging element against a stop, thus maintaining it in the normal position, but that is overcome on triggering the buckle tightener. Other designs are also possible.
In a particularly preferred embodiment, the vehicle seat has, on one side of the seat, a locking device for the angular adjustment of the swivelling prop of this side of the seat and on the opposite side of the seat it has the array with engaging element and sector gear described above. In other words, the swivelling prop hitherto described is located on one side of the seat, more specifically on that side of the seat that is located on the side of the tunnel. Another swivelling prop is provided for on the other side of the seat. The two swivelling props are non-rotatably linked to each other by a transverse bar. A locking device for the angular adjustment for the two swivelling props is provided on the other seat side only. As a result thereof, it is not necessary to transmit the lock from one seat side to the other on one hand, on the other hand, enough space is thus obtained for the described safety device comprising the engaging element and the sector gear.
In order to absorb the reaction force produced on triggering the buckle tightener, it is advantageous to sufficiently fasten a housing of the buckle tightener on the seat carrier. It is advantageously supported on the hinge joint without thereby impeding the movement of the engaging element. It may however move to a certain extent about the hinge joint. The holding means of the tightener restricts a pivotal movement of the tightener.